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Depreciation from actual usage (units of production) — per-unit rate, yearly expense, book value.
Some assets are consumed by doing, not by aging. A taxi that drives 65,000 miles in a year is genuinely more “used up” than an identical taxi driven 20,000 miles — and the activity method of depreciation turns that intuition into accounting. This Activity Method Depreciation Calculator converts your asset’s cost, salvage value, lifetime activity, and this period’s actual activity into the period’s depreciation expense, the per-unit activity rate, and the resulting book value.
Follow these steps:
Tip: pick the activity measure that best tracks wear. Delivery vehicles live by the odometer (miles), aircraft engines by flight hours or cycles, printing presses by impressions, and factory machines by units produced. A $50,000 asset with $5,000 salvage and 100,000 lifetime miles depreciates at $0.45 per mile — so 12,000 miles yields exactly $5,400 of depreciation and a $44,600 book value.
Walkthrough: a courier company buys a van for $42,000, expects $4,000 salvage, and estimates 280,000 lifetime miles. The dispatcher enters 42000, 4000, 280000, and this year’s 52,000 miles, then clicks Calculate Depreciation. The per-unit rate is ($42,000 − $4,000) ÷ 280,000 = $0.135714 per mile, and this year’s depreciation is 52,000 × $0.135714 = $7,057.14 — rising and falling with the route sheet, not the calendar.
Reading the result: the per-unit (activity) rate is the depreciation cost of one mile, one hour, or one impression — it stays constant until you revise an estimate. This year’s depreciation is that rate times actual activity. Book value after equals cost minus all depreciation charged to date, and it can never fall below salvage.
Multi-period tracking: run the calculator each period with that period’s activity and keep a running total. After year one’s $5,400 on the van, cumulative depreciation is $5,400 and the remaining depreciable base is $39,600. If year two logs 15,000 miles, depreciation is $6,750 and cumulative reaches $12,150. A simple spreadsheet with columns for period, activity, period depreciation, and cumulative depreciation gives you the full schedule — and the book value at any date.
The activity method — also called the units-of-production or units-of-activity method — allocates an asset’s depreciable cost in proportion to its actual use. Instead of asking “how old is it?”, it asks “how much did it do?” A press that stamped 110,000 parts this quarter has consumed more of itself than one that stamped 60,000, so it carries more depreciation. The method is the purest expression of the matching principle: recognize expense in the same period as the revenue the asset helped create.
Three estimates drive it. First, the depreciable base: cost minus salvage value, the total to be written off. Second, total lifetime activity: the miles, hours, cycles, or units the asset is expected to deliver across its entire working life. Third, the period’s actual activity, read from odometers, hour meters, cycle counters, or production logs. The activity rate — depreciable base divided by lifetime activity — prices a single unit of use; multiplying by period activity gives the period’s charge.
Accountants distinguish the activity method from its time-based cousins by what triggers expense. Straight-line charges the same amount every period whether the asset worked or sat idle — right for buildings and furniture, wrong for a delivery fleet. Declining-balance front-loads expense on the theory that assets lose value fastest early — right for technology, debatable for a well-maintained press. The activity method charges exactly for what was consumed — right whenever wear follows throughput and you can measure that throughput reliably.
Reliable measurement is the method’s hinge. Modern telematics, hour meters, and production counters make activity cheap to track; a clipboard estimate made once a year does not. Auditors accept activity-based depreciation readily — but they expect logs. The odometer photo, the meter download, the press counter readout: these turn an estimate into evidence and protect the deduction under review.
A note on scope: the activity method shines for financial reporting under GAAP (ASC 360), where any systematic and rational allocation is acceptable. For U.S. federal income tax, MACRS (IRS Publication 946) generally prescribes its own methods and recovery periods, so book depreciation and tax depreciation often diverge. Use this calculator for management accounts and financial statements; let your CPA handle the tax return.
Estimate discipline completes the picture. Lifetime activity is a forecast, and forecasts go stale — a taxi retired early, a press run harder than planned. Review the estimate annually; when reality diverges, compute a fresh activity rate on the remaining book value over remaining activity, applied prospectively. Prior periods are never restated.
A note on naming: “activity method,” “units of production,” and “units of activity” describe the same mathematics — textbooks and software use the labels interchangeably. Some sources reserve “units of production” for manufactured output and “activity method” for service measures like miles or hours, but the formula does not care what you call the unit. What matters is that the measure tracks wear.
The method uses two formulas:
Activity Rate = (Cost − Salvage Value) ÷ Total Lifetime Activity
Period Depreciation = Activity Rate × Activity in Period
Book Value After = Cost − Accumulated Depreciation, never below the salvage value. Total lifetime depreciation is capped at (Cost − Salvage Value).
Worked Example 1 — service van. Step 1: cost $50,000, salvage $5,000, lifetime 100,000 miles. Step 2: depreciable base = $50,000 − $5,000 = $45,000. Step 3: activity rate = $45,000 ÷ 100,000 = $0.45 per mile. Step 4: the van drives 12,000 miles this year. Step 5: depreciation = $0.45 × 12,000 = $5,400.00. Step 6: book value after = $50,000 − $5,400 = $44,600.00. Sanity check: at 12,000 miles a year the van’s depreciable base is exhausted after 100,000 miles — exactly the estimate.
Worked Example 2 — aircraft engine. Step 1: cost $800,000, salvage $80,000, lifetime 20,000 flight hours. Step 2: depreciable base = $800,000 − $80,000 = $720,000. Step 3: activity rate = $720,000 ÷ 20,000 = $36.00 per flight hour. Step 4: the engine logs 2,400 hours this year. Step 5: depreciation = $36.00 × 2,400 = $86,400.00. Step 6: book value after = $800,000 − $86,400 = $713,600.00. Airlines genuinely depreciate engines this way — by hours and cycles — because a parked aircraft does not wear its engines.
Intuition check: stack the activity method against 5-year straight-line on the $50,000 van: ($50,000 − $5,000) ÷ 5 = $9,000 a year regardless. Under the activity method, a 20,000-mile year charges $9,000 while a 6,000-mile year charges $2,700. Straight-line overstates cost in quiet years and understates it in busy ones — the distortion the activity method was built to remove. Lifetime totals agree ($45,000); only timing differs.
CityRide Taxis buys a sedan for $38,000, expects $4,000 salvage, and estimates 300,000 lifetime miles — taxis live hard. Activity rate = ($38,000 − $4,000) ÷ 300,000 = $34,000 ÷ 300,000 = $0.113333 per mile.
Year 1 the cab runs double shifts: 65,000 miles. Depreciation = 65,000 × $0.113333 = $7,366.67; book value $30,633.33. Year 2 eases to 48,000 miles: depreciation = $5,440.00; book value $25,193.33. Under 4-year straight-line both years would show $8,500 — flattering the brutal first year and punishing the gentler second. The activity method tells the truth: the car consumed $7,367 of itself in year one and $5,440 in year two.
The rate doubles as a pricing input. Every dispatched mile consumes $0.1133 of vehicle, so CityRide’s per-mile fare must clear that plus fuel, driver, insurance, and margin before it earns a cent. Operators who price from straight-line averages undercharge on heavy-mileage routes — the activity rate keeps quotes honest when utilization spikes.
CityRide’s control is the odometer log, photographed monthly and reconciled to dispatch records. When a cab is reassigned to airport duty (higher annual miles), the lifetime-miles estimate gets reviewed — not because the method failed, but because the forecast changed. That annual review is the method working as designed.
Meridian Print installs a press for $180,000 with $18,000 salvage and an engineering estimate of 50,000,000 lifetime impressions. Activity rate = ($180,000 − $18,000) ÷ 50,000,000 = $162,000 ÷ 50,000,000 = $0.00324 per impression.
This year the press runs 9,200,000 impressions: depreciation = 9,200,000 × $0.00324 = $29,808.00; book value falls to $180,000 − $29,808 = $150,192. Cost of goods sold now carries the true equipment cost of every impression — $0.00324 — so Meridian’s per-thousand-impression quotes embed depreciation automatically. A slow year at 5,000,000 impressions would charge only $16,200, protecting margins exactly when revenue is thinnest.
Next year the press runs 10,500,000 impressions: depreciation = 10,500,000 × $0.00324 = $34,020.00, and book value falls to $150,192 − $34,020 = $116,172. Cumulative depreciation is now $63,828 against the $162,000 depreciable base — 39.4% consumed, matching the 39.4% of lifetime impressions used (19,700,000 ÷ 50,000,000). That self-check — percent of base consumed equals percent of activity used — is the fastest way to verify any activity-method schedule.
Suppose a $22,000 rebuild in year four extends life by 8,000,000 impressions. The rebuild is capitalized: depreciable base and lifetime activity both rise, and a fresh activity rate is computed prospectively on the remaining book value. Routine consumables — ink, blankets, routine service — are expensed. Capitalize what extends life or capacity; expense what merely maintains it.
One habit neutralizes all five mistakes: keep a fixed-asset register recording, per asset, the cost, salvage value, lifetime activity, activity measure, cumulative activity to date, and the resulting activity rate — refreshed from meter readings every period. Ten minutes per asset per period keeps the method credible.
And a bonus pitfall: forgetting to revise the lifetime estimate. A taxi moved to gentle suburban duty will outlast its 300,000-mile forecast; a press run triple-shift will not reach 50,000,000 impressions. Annual estimate reviews with prospective rate adjustments are standard practice — the revision is evidence of control, not error.
Comparing methods? Our Depreciation Calculator runs straight-line, declining-balance, and other schedules so you can see how timing differs for the same asset. Then browse all Financial Calculators for loans, savings, and investment planning tools.
A telling exercise: run the $50,000 van through both this page (12,000 miles → $5,400) and the depreciation calculator’s 5-year straight-line schedule ($9,000/year). The $3,600 gap is pure timing — profit reads higher under the activity method in light years and lower in heavy years, exactly as the matching principle intends.
Activity Method Depreciation (units-of-production / units-of-activity): usage-based depreciation charging expense by measured activity. Formulas: Activity Rate = (Cost − Salvage Value) / Total Lifetime Activity; Period Depreciation = Activity Rate × Activity in Period; Book Value After = Cost − Accumulated Depreciation (floor: salvage value). Inputs: asset cost ($), salvage value ($), lifetime units (activity measure), units used in period. Outputs: period depreciation ($), depreciable base ($), per-unit rate ($/unit), book value after ($). Key facts: matches expense to usage via the matching principle; total depreciation capped at cost minus salvage; GAAP-accepted (ASC 360); U.S. tax generally follows MACRS instead; requires reliable activity measurement; estimates revised prospectively. Reference values: ($50,000 − $5,000)/100,000 = $0.45/unit → 12,000 units = $5,400.00, book value $44,600.00; ($800,000 − $80,000)/20,000 hrs = $36.00/hr → 2,400 hrs = $86,400.00.
Sources: ASC 360 (Property, Plant, and Equipment) for systematic allocation; IRS Publication 946 for U.S. federal MACRS tax depreciation context. Confirm tax treatment with a professional.
Depreciation tied to actual use — miles driven, hours run, or units produced — instead of time. Heavy-use years show more expense than idle years.
(Cost − salvage) ÷ total lifetime units gives the per-unit rate; multiply by units used this period. The calculator above does it instantly.
For assets whose wear follows usage, not age — delivery trucks (miles), factory machines (units), aircraft (flight hours).
Straight-line is simpler and spreads cost evenly; the activity method matches expense to real wear but needs usage tracking.
No — total depreciation over the asset's life is capped at cost minus salvage value, and book value never drops below salvage.